Method of making refracting and diffusing containers for incandescent lights.



P. c HEWITT. METHOD OF MAKING REFRACTiNG AND DIFFUSING CONTAINERS FOR INCANDESCENT LIGHTS. APPUCATXON FILED JUNE. 1914. a

1, 177,326. Patented Mar. 28. 1916.

cifigaz Z INVENTOB H9561 Cyerfizwiii HIS ,4 NORA/E) by difiusion a softening of the lIght.-

f In my prior application, Serial No. 619333,

filed April 8, 191-1. and my prior Patent PETER sootn HEWITT, orm'uewoon Manon, NEW JERSEY.

monenmme BEER-norms AND mrrosme coura u nears.

Specification of Letters Patent.

Patented-Mar. 2S,-1916.

Application filed um: 17, 1914. Serial No. 845,720.

To all wkom it mag/concern dent of Ringwood Manor, in the county of Passaic and State of New Jersey, have inented certain new and useful Improvements in Methods oil-Making Refracting and Diffusing Qontainers for Incandescent Lights, of which the following-is a specification.-

'My invention is especially applicable. for

use in treating an incandescent lamp bulb so as to provide means for changing the direction of the light rays therefrom to permit the better illumination of objects in a desired direction from the lamps,-and to secure No. 1,036,527 issued August 20, 1912, I have disclosed and'claiinedan invention of mine -particularly applicable to the ordinary commercial tungsten gfila'ment and other iiicandescent lamps. In the preferred embodi- ,ment I disclose the use'of etched' groove-like markings on the bulb so narrow and so closely spaced that when viewed from ordinary distances, rays from any given length I of filamenhseparately scatteredslaterally by each of a multiplicity ofthe-'groove-like 1markings,blend in the field of illumination, and cause said length of filament to have the optical appearance of a widened band, or a transversely continuous surface of light, the width of which is practically independent of the diameter of the filament, but is dependent upon the shape, angle and spacing ofthe efiectively; contributing groove-like .mark- '1 ings.

By arrangmg the markings at an angle to the general direction of the filaments and properly proportioning the steepsidedmess-and close spacing of thegrooves to the angle of the projected length of the grooves with the projecteddength of-the filament, the ridges will act as refractors to direct lightto points deficient in luminosity. At the same time, the filament lengths are each apparently widened out so as to produce upon the eye of the observer, the effect of a single substantially continuous flame or cloud of light inside of the container, or the, effect of a continuous -l1ght-giv1ngsurface,

or both, although the distribution of'light in the various. parts .of said flame cloud or surface may vary inrintensity. appear-,

the I Q I ance thus given of a single continuous blaze .lie-ihknown that I, PETER COOPER HEW- ITT, a citizen of the United States, and resiof light emitted through a wide area may in- E'Es Eon INcAunE'scEN'r clude the whole orv a large .portion ofthe '7 large part of the interior of the globe. The

source and a decreasing of the intensity, without loss of light, is thus secured not only by the lateral widening effect of the filament, but also by the directing of a portion of the'light from what was otherwise the zone of maximum illumination to the dark spots or zones which in ordinary lamps are formed adjacent the projected longitudinal axis of the filaments and lamp.

I have discovered that by making the grooves sufliciently steep-sided and correspondingly closely spaced, the grooves may, in pract1ce,be arranged diagonally or, owing to the curvature of the bulb and irregularity of the filament lengths, even at right angles.

to the general direction or common a'vis about which the lengths of filament are la-r ranged. Even "though a considerable portion of .some one filament may appear inef fectively' widened from certain view points, nevertheless, if the grooves are suificiently steep-sided and sufiiciently'closely spaced, a large proportion of the total zig -zag filamentary lengths-will be at such angles as to be effectively widened and productive of a practically continuous surface of light. This is attainable through practically polished groove-likemarkings closely spaced and arranged at-right angles to the axis of the lamp, and hence not more than, say 10 to 25 from right angles to the projected length .of some portions of-some of the lengths of filament. -The slight irregularities in cross sectional formation and'lateral spacing of the grooves due to inaccuracies of the ruling or action of the acid, contribute to this same result. By the term polished? .I mean transparent in contradistinction to frosted.

or opaque. In other words, a surface in which there is no material loss of light by absorption or complete-reflection. v

My present inyeiition involves a method which I have discovered wherebygrooves may be etched with the "i'eqliired;"tlegree of the purpose istojdeflect'light 'precision' and .steep-sided-ness.necessary to secure extreme deflecting action which 1s" required where into a dark zone lying in th axis of'the lamp. This requ red COIISEClQIEltlOIl of minute causes and effects to secure results not necessary in a case where the grooves and ridges are arranged approximately parallel ployed for making grooves parallel to the axis. It can be used lfOl making grooves extending in any direction and on any suitable surface and for various other purposes than light refracting, but its greatest utility,

so far as I am at present aware, is in the production of lamps of the character herein described.

In order to get approximately semi-circular grooves sufliciently near tangent to give sharp ridges with knife-like orcold chisel edges alfording the maximum lateral deflection required for the special purposes of my .present invention, I have discovered thatv the grooving of the initial protective coating must be extremely'regular and that a the Width of the exposed surface of theglass at the bottom'of the groove should be small as compared with the distance between-the grooves even in the cases where the total distance is only 1/100th inch or less. By pressing these grooves with an edge rather than attempting toplane them out-with a.

chisel-like point, the width of the whole surface or l/lOOth of an inch spacing may be approximately 1/5th of that distance or say 2/1000th of an inch. This expedient results in starting the action of. the acid along the relatively thin line or axis so that if the corrosion uniform the resulting groove should be a semicircle. .I have fur,- ther discovered. that the action 'of the acid in eroding the glass in all directions-from s 10h an axial line results in causing anoutwardly expanding mechanical forcing by I the confined products of the reactlon. This results in progressively pushing outward the overhanging edges of the wax and success in maintaining the desired semicircular or equal radius erosion of the glass requires that the coating be of such material and so.

applied that only the free or overhanging portion will bend or break outward under the expansive force of the reaction, and

while the adhesion of the remaining. por-,

tion of the coating to the original glass surface will remain so perfect that no fresh exterior surface of the glass will be exposed to the even action of the acid, thepurpose and the result being that all erosion progresses uniformly from. the original exposed .line as an axis. In practice -th8;fiC1d may eat slightly more rapidly along a line directly opposite and lyingat the bottom of I the groove, but in general and Within limits the result will be tangent semicircles with very sharp edges.v

Byemploying my improved processand. by employing the relative arrangement of grooves and filaments herein described, a-'.

large portion of .the light from -an'.incandescent lamp supported overhead with substantially vertical filaments may be directed downwardly, and at the same time may be softened by a very efi'ectivelateral compo nent of -the light-retracting eifectsof the grooves. By arranging the markings withv each having a material component at right angles to thegeneral directionof the fila- 'ment, most ofthe'v light rays from any point on the sourbe will'be refracted so that they diverge in a. plane at right angles to the groove-like markings or ridges-on the sur'-' 'face of the container.

I If these 4 extend around the cont'a er in a general direction at right angles iii 'theseries of filaments, the light may be given a strong [downward component, such component depending on the steep sidedness of the- .refractors and the angle the interior surface makes with the filament, and made to shed light on the normal dark spots of the bulb.

If the bulb or other container'be spherical or otherwise formed with equal portions of the Vertical filamentor other source oflight above and below the .plane of the maximum. diameter of the container, and the defractors' or prism-like bodies formed by themarkings encircle the. source of light either in concentric circles or concentric he'lixes, there will be a-directive actiondue to the angle of the inner surface to the filament, toward both ends of the container, and the light rays emitted will be divided into two portions which will be refracted away from each other upon opposite sides of the plane of, maximum diameter-of the bulb. "Thusobjects at each end of the bulb or other container will be illuminated to a higher. degree than they would were the surface plane.

It is not essential that the grooyes be'absolutelyuniform as slightirregularities in the width, shape and depth of the grooves" may be present without materially modifying the directive action of the prisms, and it mayeven add to the. diffusing action. F urthermore, the shape of successive grooves may be intentionally varied so that the groovesadjacent to the ends of the bulbs may be of different refractive power than those opposite the center of the filament.

Thus successive grooves or markings may be varied to secure a more effective distributing or directing action. Although the most effective directing action will be produced.

' when the grooves lie in planes at right anglesto the linear source of light, yet a very efit'ective and highly desirable directing ac? tion toward the ends of the bulb may be pro- 1 duced with the prisms disposed helically around the bulb, Under certain circumstances, it may be desirable to have the lines or markings running indifferent directions and different angles on diflerent parts of the container, so as to accentuate or modify the directive action. A

By etching the grooves extremely narrow, I am able to secure the desired steepsidedness without cutting the grooves to an objectionable depth. The narrower the grooves, the shallower may they be with the same steepsidedness, and the less will the wall of the bulb be weakened by the removal of material, Furthermore, the narrower and shallower the grooves, theless material willv have to be removed and the quicker may the etching.

In the accompanying drawings, forming a' part of this application, Figure 1 is a side elevation of an incandescent lamp of substantially spherical form and having the groove-like markings extending around the lamp substantially at right angles to the axis thereof; Fig. 2 is a side elevation of a lamp having the filaments disposed entirely at one side of the transverse plane of maximum diameter and marked similarly to the form shown in F 1g. 1; and Fig. 3 1s aside elevation of the ordinary pear-shaped incandescent light, having the markings helically disposed and with the major portion of the separate filamentary lengths below the plane of maximum diameter; and Fig. 4 is a section transversely of the grooves and on a greater enlarged scale.

In carrying out .my invention, I- preferably utilize the ordinary commercial incandescent electric lamp, butit is not limited to any particular form or type of construction.

In the drawings, I have illustrated in Fig. 1,

a lamp having a substantially spherical body of blown glass and of commercial thinness.

Within the bulb is suppbrted the light-emit-- ting filament, which may be arranged inzig zag form and supported upon arms as in the ordinary tungsten lamp of commerce, or

may be supported as in the ordinary carbon filament lamp. The form and arrangement of the filament does not involve any feature of my invention, except inso far as the relative positioning and direction of the filamentary lengths and the light-deflecting grooves or markings on the surface are concerned.

The lamps illustrated have the filaments extending in the same general direction as the maior or longitudinal axis of the bulb;

Upon the outer surface of the bulb. I provide minute ridges or grooves 11, which extendin the direction having a material component at right angles to 'the projected lengths of the filaments. These grooves or ridges are very minute and are closely spaced, and their sides areof such steepness as to give a material light-directing-action at an angle to the general direction of the grooves. These grooves or ridges are preferably formed by coating the outer surface 7o of the bulb with a fine skin of wax, asj phaltum, or other similar acid-resistingmaterial, and then outing or scratching through the wax for the purpose of exposing the surface of the glass along: lines properly spaced and of suitable width. The bulb may then be immersed inhydrofiuoric acid, and in desired form, condition, dilution or admixture, for the proper length of time, or in place of hydrofluoric acid solution, the bulb 30 may be exposed to hydrofluoric gas. Upon subjecting the bulb to'the action of the'chemical for the proper-length of time and then cleaning off the remaining wax,'the oper'ation will! be completed. p 35 I make the grooving-of the initial protective coating extremely regular and the width of the exposed surface of the'glass at the bottom of the groove smallas compared with the distance between the grooves even in the cases where the total distance is only l/lOOth inch or less. By pressing these grooves with an edge rather than attempting to plane them outwith a chisellike point, the width of the exposed surface for 1/ th of an inch spacing may be approximately 1/5th of that di'stance-orsay 2/1000th of an.inch. Thus the action of the. acid starts alongthe relatively thin line or axis so that if the corrosion is uniform the 10,0

resultinggroove should be. a semi-circle. 'The action of the acid in eroding theglass in all directions from such an axiallme results. in causing an outwardly expanding mechanical forcmg by the confined products of the reactlon. This results in progressively "pushing outward the overhanging edges of the wax and success in maintaining the desired semicircular or equal-radius erosion of the glass requiresthat the coating be of such material and so applied that only-the free or overhanging portion will bend or break outward under the expansive glass and lying at the bottom of the. groove, 12':

and within limits the result will be tangent semicircles with very sharp edges. I, I

I have discovered thatithetdesired perfee j but in general and the desired narrowness of the grooves,

. and the desired approximation of perfect semicircular erosionmay be attained on a commercial tungsten vacuum bulb lamp, as follows: I first dissolve 100 grams of Standard'Oil 300 oxidized asphalt in 500 cublic centimeters of chloroform. I then" dip the lamp in this solution,.and upon removingit, heat to about 180 centigrade for ,a .few minutes to cause the asphalt to ad- "here firmly to the glass.- I then rule the asphalt with a tool making lines 1/l00 of an inch apart. Etch with 48% commercial hydrofluoric acid slightly diluted and having added to it cubic centimeters of hyd rocholoric acid to the pound of commercial hydrofluoric acid, being about 4%. The etching is then continued from five to fifteen minutes denending'on the temperature and freshness'of the acid. I thenwash carefully and dry. Grooves formed in this manner have knife-like or cold-chiseled edges as distinguished from the rounded edges disclosed in my prior patent above referred to. is largely due-to the fact that the adhesive coating does not chip off during the etchrefract the light rays laterally from the outer ing .and that the etching progresses in- Wardly and laterally upon opposite sides of the ridges but cannot act upon the top of the ridge. I Y

The grooves may be madeas large'as 1/3Qth of an inch or even. larger, and as small as 1/250thof an inch or smaller, from center to center depending on the usedesigned fcr and practical reasons of economy and manufacture, and the, steep sidedness trolled that the surfaces of the grooves are.

substantially smooth or polished, so that there is practically none of the loss which occursin the ordinary frosted bulb.

lVith the filaments extending in the same general direction as the major or longitudinal axis of. the bulb. I may form the markings around the bulb at substantially. right angles to the longitudinal axis. as is shown in Figs. 1 and 2. The small ridges of glass between adiacent grooves act as prisms and angle or edge of the prism. Thus, each light ray in traveling outwardly at right angles to the filament will be bent towardeither one end or the-- other of the bulb. \Vith the bulb substantially spherical, as shown in Fig.1. and with the filaments positioned opposite'to the major diameter of the bulb there will be an equal light-defecting action towardlboth ends ofthe bulb.

As previously explained, this If it is desired to secure a larger lightdirecting' action'toward one end than toward the other, for instance, on a. bulb which is to be supported overhead and illuminate objects beneath it, I may apply my process to a bulb 12 substantially conical in form, as shown in Fig. 2, and.position the filaments entirely on one side of the plane of the major diameter. Thus, all of the bulb wall directly opposite to the filaments will be inclined toward an apex and a larger portionof .the light rays traveling outwardly at right angles to the filaments will be directed in the general direction of the apex of the bulb than will be directed toward theflatter end or base. Substantially the same results may be secured by employing a bulb 13 of the ordinary commercial form, 'as shown in Fig. 3. In this case, the major portion of the bulb walls are inclined inwardly toward the socket instead of toward the tipas in Fig. 2. In this form, I have illustrated the groove-likemarkings arranged helically, so that the angle between the grooves and the projected lengths of the filaments will be not quite as great as in the annular arrangement of markings shown in. Figs. 1 and 2; The inclination or pitch of the grooves may be varied at will, but the greater the angle between the projected length of grooves and filaments, the greater will be the directing action in the general direction of the lengths of the filaments.

A variation in the angular arrangement of groovesand filaments may be counter- .of groove-like markings and will blend in.

the field of illumination. Each length of filament will have not vonly the optical ap-' pearance of a widened band or transverselycontinuous. surface of light, but each of'said bands may appear elongated substantially to the tip of the bulb, and the bulb when viewed fromthe end may present a substantially uniform field of illumination eloselv approximating the illumination at the sides of the bulb. If the filaments be arranged in some other form than in the general directio-n' of the length of thebulb,

vitjis evident that the direction of the groovelike markings may be correspondingly varied to secure the like results, and with other forms of light be modified accordingly.

"actedby a variation in the steep sidedness'of I -Iaving thus described my invention, I cla1m as new anddesire to secure by Letters Patent:

1. The herein described method of pro-- ducing a light refracting surface which, consists in coating a glass surface with an adhesive compound, ruling through said coating a series of substantially parallel narrow lines, and etching grooves in said surface along said lines, sa1d grooves being materially wider than said lines in-said coating,

and the etching being continued until said grooves approximately meet beneath the portions of coating between said lines.

thin. adhesive layer, ruling through saidlayer a series of closely-spaced narrow lines,

.and etching grooves in the glass through said lines, the etchingbeing continued until, said grooves approximately meet to leave knife edges there-between.

4. The herein described process *whi'ch l consists in coating a glass surface with a thin adhesive layer, ruling through said layer a series of closely-spaced narrow lines, and etching semi-circular grooves in the glass through said lines and of greater width than said-lines, the etching being con tinued until said grooves approximately meet to leave kni'fe edges there between, and the said adhesive layer being of such thickness, composition, and a'dhe'siveness, as to break away upon the continuing of -'the etching process beneath the layer, but with- I out exposing additional glass surface.

5. The herein described process which consists in applying a thin adhesive-coating to the outer surface of a glass electric light bulb of the incandescent type, ruling through said coating a series of closely spaced, narrow lines encircling the source of the major axis of said bulb, grooves in the glass through sald lines, the

etching being' continued until adjacent light and approximately at' right angles to l and etching groves approximately meet to leave narrow ridges therebetween.

Signed at New York city-in the county of New York and State of New York this 26th day of May, A. D. 1914. v

. PETER COOPER HEWITT.

Witnesses;

R. A. HEWITT, C. W. FAmBA-NK. 

